Friday, September 10, 2010

Speed P6 2010 SA2 River Valley P2 Q16

A rabbit and a tortoise competed in a 5.2 km race. The rabbit ran at a speed of 20 km/h while the tortoise’s speed was 3 km/h. The tortoise ran continuously to complete the race. However the rabbit ran for 1 min and rested for 20 min. It ran the next 2 min and rested or 20 min. It then ran for the next 3 min and rested for 20 min and so forth. At this rate, how many minutes more would it take the rabbit than the tortoise to complete the race? [5 marks][Answer given: 11.6 min]


Time for rabbit
5.2/20 x 60 = 15.6 min

15 = 1 + 2 + 3 + 4 + 5 + 0.6

20 x 5 = 100 min

100 + 15.6 = 115.6 min

Time for tortoise
5.2/3 x 60 = 104 min

115.6 - 104 = 11.6 min more

It was 11.6 min more.

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